DESCRIPTION: Cancer remains the second leading cause of death in developed countries. A cancer-associated protein was recently discovered during evaluation of antibodies. This protein, like telomerase, was abundantly expressed in 85 percent of tumor cell lines and malignant tumor tissues from patients with lung, breast, brain, or kidney cancer but was detected in only 3.4 percent of normal cells and tissues. It has the features of oncofetal proteins and telomerase but is identical neither to telomerase nor to the protein from which the antibody generating peptide was selected. Thus, this protein appears to be a novel cancer antigen. The expression levels of the protein in a variety of cancer tissues, particularly lung cancer, will be characterized in this proposal. It will be identified by protein purification using a combination of immunoaffinity chromatography and 2D gel separation and sequencing of the purified protein and digested peptides, by phage expression library screening and cDNA sequencing, and by bioinformatic approach. The long-term objectives are to isolate the gene encoding this protein, to develop screening and diagnostic kits, and to define a therapeutic target for cancer. This protein has a large market potential for the development of diagnostic kits and the design of therapeutic drugs for cancer. PROPOSED COMMERCIAL APPLICATION: Characterization and Identification of this novel cancer-associated protein has potential not only in screening diagnosis, prognosis, and monitoring of cancer, but also has potential in molecular and genetic studies of tumor development as well as in being a target for cancer therapy. This novel cancer-associated protein has a large market potential for the development of reserch reagents, diagnostic kits, and therapeutic drugs for cancer.